3. Early Theories of Evolution
Lamarckian Theory ( )
Lamarck believed living things:
changed over time
adapted to their environment

4. 3 Hypotheses 1. A desire to change An inborn urge to better themselves
Ex. Birds desired to fly → wings

6. 2. Use and Disuse
Organism could alter body shape by using their bodies in new ways
Ex. Snakes, giraffes

9. 3. Passing on of traits
If an animal acquired a trait during its lifetime, it could pass the change on to its offspring
Ex. Weightlifter’s muscles

11. All of the above are fallacies associated with evolution

12. Charles Darwin
1831 traveled around the world and collected plant and animal species on the HMS Beagle
Published On the Origin of Species by Means of Natural Selection in 1859

13. Chapter 15
Evolution
15.1 Darwin’s Theory of Natural Selection
The Galápagos Islands
Darwin began to collect mockingbirds, finches, and other animals on the four islands.
He noticed that the different islands seemed to have their own, slightly different varieties of animals.

15. Darwin Continued His Studies
Chapter 15
Evolution
15.1 Darwin’s Theory of Natural Selection
Darwin Continued His Studies
Darwin hypothesized that new species could appear gradually through small changes in ancestral species.
Darwin inferred that if humans could change species by artificial selection, then perhaps the same process could work in nature.

16. Artificial selection: the process of directed breeding to produce offspring with desirable traits

17. Natural Selection: theory that organisms best adapted to the environment will out compete those who aren’t and will survive

18. 4 Basic Principles 1. Individuals in a population show variations
2. Variations can be inherited

19. 3. Organisms have more offspring than can survive on available resources
4. Variations that increase reproductive success will have a greater chance of being passed on

20. Evolution: cumulative changes in groups of organisms through time
Groups evolve, not individuals

21. Darwin’s theory of natural selection is not synonymous with evolution.
Chapter 15
Evolution
15.1 Darwin’s Theory of Natural Selection
Darwin’s theory of natural selection is not synonymous with evolution.
It is a means of explaining how evolution works.

22. Theory of Evolution: all organisms on Earth have descended from a common ancestor

23. 15.2 Evidence of Evolution Support for Evolution 1. The fossil record
Chapter 15
Evolution
15.2 Evidence of Evolution
Support for Evolution
1. The fossil record
Fossils provide a record of species that lived long ago.
Fossils show that ancient species share similarities with species that now live on Earth.
Glyptodont
Armadillo

24. Archaeopteryx

26. Fossil has characteristics that classify it as a bird, but retained several obvious dinosaur characteristics

27. Convergent vs. Divergent Evolution (Background)

28. Support for Evolution 2. Comparative Anatomy
Homologous structures: anatomically similar structures inherited from a common ancestor

29. The structures may move in different ways, but they share similar construction

30. Ex. Bird wings and reptile limbs

33. predicts that features of ancestors that no
Chapter 15
Evolution
15.2 Evidence of Evolution
Vestigial Structures
Structures that are the reduced forms of functional structures in other organisms.
Evolutionary theory
predicts that features of ancestors that no
longer have a function for that species will
become smaller over time until they are lost.

34. Other examples?

35. Kiwi Bird

36. Chapter 15
Evolution
15.2 Evidence of Evolution
Analogous structures can be used for the same purpose and can be superficially similar in construction, but are not
inherited from a
common ancestor.

37. Show that functionally similar features can evolve independently in similar environments

40. 3. Comparative Embryology
Chapter 15
Evolution
15.2 Evidence of Evolution
3. Comparative Embryology
Vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms.

42. 4. Comparative Biochemistry
Chapter 15
Evolution
15.2 Evidence of Evolution
4. Comparative Biochemistry
Common ancestry can be seen in DNA and amino acid sequences

43. 5. Geographic Distribution
Chapter 15
Evolution
15.2 Evidence of Evolution
5. Geographic Distribution
The distribution of plants and animals that Darwin saw first suggested evolution to Darwin.
Rabbit
Mara

44. Evolution is intimately linked with climate and geological forces.
Chapter 15
Evolution
15.2 Evidence of Evolution
Patterns of migration were critical to Darwin when he was developing his theory.
Evolution is intimately linked with climate and geological forces.

45. Usually measured by number of healthy offspring
Chapter 15
Evolution
15.2 Evidence of Evolution
Types of Adaptation
An adaptation is a trait shaped by natural selection that increases an organism’s reproductive success.
Fitness is a measure of the relative contribution an individual trait makes to the next generation.
Usually measured by number of healthy offspring

46. Camouflage: allows an organism to blend in with its environment
Chapter 15
Evolution
15.2 Evidence of Evolution
Camouflage: allows an organism to blend in with its environment
Allows organisms to become almost invisible to predators
Leafy sea dragon

47. Camouflage

48. One species evolves to resemble another species.
Chapter 15
Evolution
15.2 Evidence of Evolution
Mimicry
One species evolves to resemble another species.
Western coral snake
California king snake

49. Consequences of Adaptations
Chapter 15
Evolution
15.2 Evidence of Evolution
Consequences of Adaptations
Some features of an organism might be consequences of other evolved characteristics.
They do not increase reproductive success.
Features likely arose as an unavoidable consequence of prior evolutionary change.